Preparation of cores for analysis



June 28, l96 J. D. BENNETT 3,258,209

PREPARATION OF CORES FOR ANALYSIS Filed Aug. 5, 1965 Liquid Exhaust CO2 26 Cyclone \zl 2 Separator 24 22 23 9 k C. 28 I8 I Core Disinfegrotor l6 3o 7 LL 3| INVENTOR.

JOHN D. BENNETT ,fw

ATTORNEY United States Patent 3,258,209 PREPARATION OF CORES FOR ANALYSIS John 1). Bennett, Dallas, Tex., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Filed Aug. 5, 1963, Ser. No. 299,790 3 Claims. (Cl. 241-62) This invention relates to the preparation of cores for geological analysis, and more particularly to a method and apparatus for the disintegration or disaggregation of cores.

In geological work, it is very desirable to be able to examine the parts of a core, and especially to be able to determine the sizes of the grains that were laid down when the core was originally formed. For the geologist to be able to examine the core properly and correctly, the agglomerated core must be taken apart or disintegrated (disaggregated).

There are several known methods for taking cores apart. One utilizes a chemical process wherein the cementing agent is dissolved; however, this process has a tendency to dissolve the grains themselves, which obviously interferes with the proper determination of grain size. Another utilizes a hammering blow; however, this tends to crush the grains of the core, giving a grain sample that is not typical. Still another utilizes -a tumbling process; however, this tends to abrade or wear (erode) the grains, again giving a grain sample that is not typical.

An object of this invention is to provide a novel core disintegrator.

Another object is to provide a core disaggregator which subjects the parts of the core to the least amount of stress possible, thus avoiding the drawbacks associated with the known methods of core disintegration.

A further object is to provide a mechanically-acting core cracker which forces the individual grains from their adjoining grains.

The objects of this invention are accomplished, briefly, in the following manner: The core or sample is separated into its parts or disintegrate-d by the use of internal pressure. The core is inserted into a pressure vessel or cell which is provided with a means (e.g., a rupture disc) by which the pressure in the cell can be suddenly released or reduced; this release is effected through a sudden increase in the volume of the vessel when the disc closure ruptures. After the core is inserted in the vessel, a compressible fluid (e.g., liquid carbon dioxide) is pumped (fed) into the cell at -a slow rate such that the fluid can enter into the pores of the core. A high pressure builds up in the vessel. At some prearranged pressure, the rupture disc closure breaks, suddenly releasing the energy which has been stored in the compressible fluid (by suddenly reducing the pressure in the cell, as a result of the sudden increase of volume which occurs when the disc closure breaks). This sudden release of the internal energy (stored by the fluid within the core) causes the core to pop open or explode, forcing the individual grains of the core apart. When the pressure is thus released, the liquid in the vessel bashes into a gas. A cyclone-type gas-solids separator is coupled to the vessel, to release the high-pressure gas and save that part of the disintegrated core which would otherwise tend to be carried away by the gas.

A detailed description of the invention follows, taken in conjunction with the accompany drawing, wherein:

FIG. 1 is a longitudinal section through a pressure vessel used in the core disintegrator system of this invention; and

FIG. 2 is a schematic diagram of the complete core disintegrator system, including the pressure vessel of FIG. 1.

Referring first to FIG. 1, a cylindrical pressure vessel or cell, denoted generally by numeral 1, is formed from a Patented June 28, 1966 suitable metal and has rather thick walls, so that it can withstand a pressure of 10,000 p.s.i. or more. Vessel 1 has an elongated intern-a1 more or less cylindrical chamber 2 dimensioned to receive a core 3 which is to be disintegrated or disaggregated. In use, the vessel 1 may be positioned as illustrated in FIG. 1, with its longitudinal axis substantially horizontal.

A plug-type closure 4 closes the left-hand end of chamber or cavity 2, closure 4 being secured in position (to withstand the design pressure) by means of male threads 5 thereon (of Acme type, for example) which engage corresponding female threads provided in the wall of chamber 2, at one end thereof. An O-ring 6, mounted in a groove in the plug end of closure 4, near the inner end thereof, provides a seal against the cylindrical wall of chamber 2. A handle 7, one end of which is secured to the outer end of closure 4 and which extends transversely with respect to the axis of vessel 1, enables closure 4 to be screwed into or unscrewed from the vessel. Closure 4 provides for access to chamber 2 within vessel or cell 1. The cylindrical portion of chamber 2, to the right of the inner or right-hand end of closure 4, may have a length about 1%", while the diameter of the chamber may be 1%". The core 3 which is to be fractured or disintegrated may be inserted into this latter or open portion of chamber 2, when closure 4 is removed from vessel 1; following this insertion, closure 4 is screwed into closed postion (by means of handle 7) before the actual disintegration procedure begins.

A transverse hole 8 is drilled entirely through the side wall of vessel 1, into the core-receiving portion of chamber 2. The outer end of this hole is enlarged in diameter and tapped, to receive therein the threaded end fitting 9 on a pipe or tube for conveying pressure fluid to chamber 2.

The right-hand end of chamber 2, beyond the cylindrical portion of this chamber, is tapered down frusto-conically, and a central longitudinal hole 10 is drilled entirely through the end wall of vessel 1, at the apex of this frusto-conical portion, into chamber 2. The outer end of hole 10 is enlarged in diameter and tapped, to provide (at the bottom or left-hand end of this enlargeddiameter portion) an annular shoulder 11. Positioned on shoulder 11, and held thereagainst by a threaded end fitting or coupling 12 on -a pipe or tube 13, is a rupture disc 14. Disc 14 is made from thin metal stock (its thickness being greatly exaggerated in FIG. 1 for purposes of clarity), and is designed to rupture at a certain superatmospheric pressure. In this connection, it is pointed out that the left-hand face of this disc is exposed to the interior of chamber 2 (in which a superatmospheric pressure may be built up, as will be subsequently explained), while the right-hand face of disc 14 is exposed to atmospheric pressure, only.

To utilize the vessel 1 for core disintegration or disaggregation purposes, it is connected into a system as illustrated in FIG. 2. The vessel 1 is supported by a fixed support in any suitable manner (not shown), with its longitudinal axis substantially horizontal. Assume that a core 3 has been previously inserted into the vessel, as illustrated in FIG. 1. Assume also that an imperforate rupture disc 14 has been placed in position on shoulder 11.

A tube or pipe 15 is coupled to the outer or free end of fitting 9, to supply high pressure fluid (by way of this pipe and fitting) to chamber 2. A supply of compressed gas, such as a bottle 16 of nitrogen at a pressure on the order of 2,000 psi. is coupled through a shutoff valve 17 (manually operated) to a T junction 18 in line 15, from which junction a coupling extends by way of another valve 19 and fitting 9 to the chamber 2 in vessel 1.

A pressure gauge 20 is coupled to line15, for indicating the pressure therein.

A supply 21 of liquid carbon dioxide is connected through a check valve 22, a manually-operated highpressure pump 23 (which may be a two-stage pump), and another check valve 24 to junction 18. In some cases, the pump 23 may include, as built-in parts thereof, the check valves 22 and 24.

A cyclone separator 25 of conventional type, having a tangential input and a central exhaust pipe 26 leading to the atmosphere, is mounted on a fixed support 27. The pipe or tube 13 which, as previously described, is coupled to vessel chamber 2 when rupture disc 14 breaks or ruptures, provides the input for separator 25. The lower f-rusto-conical portion 28 of separator 25 is normally held in engagement with the cylindrical portion thereof by means of a plunger 29 whose upper end (provide-d with a seat) engages the bottom of portion 28. Plunger 29 passes through a hole in support 27, and the lower end of this plunger rests on a cam 30 which is pivotally mounted on a plate 31 secured to the underside of support 27; an operating handle 32 is operably secured to cam 30, for rotating the same. Thus, by operation of handle 32, cam 30 may be rotated to lower or raise plunger 29, so as to remove separator portion 28 from, or secure portion 28 to, the cylindrical body of the cyclone separator.

In operation, assuming that the system is assembled as illustrated in FIG. 2 and that a core to be disintegrated or disaggregated is in position in vessel chamber 2, valves 17 and 19 are both opened to charge chamber 2 with nitrogen at about 2,000 p.s.i. This gas readily penertrates into the pores of the core.

Then, valve 17 is closed (valve 19 remaining open), and pump 23 ismanually operated to pump liquid carbon dioxide from supply 21 into chamber 2, by way of valves 22, 24, and 19. The pumping of the liquid into the vessel or cell 1 should be done very slowly, so that such liquid can enter into the pores of the core. As the fluid penetrates into the pores of the core, any gases or air (including of course the nitrogen with which the vessel chamber 2 was initially charged) that were in the core at the time the liquid started entering, are compressed. The pressure in chamber 2 rises (this can be observed by watching gauge 20).

At some predetermined pressure (on the order of 10,- 000 p.s.i. for example), the rupture disc 14 (which up to this time has sealed the right-hand end of chamber 2) bursts or ruptures, suddenly releasing the energy which has been stored in the compressible fluid. This release of pressure occurs because, when rupture disc 14 breaks, the

chamber 2 is suddenly opened to the atmosphere (by way of separator 25). This sudden release of pressure causes the core to pop open, explode, or disintegrate, because of the restriction to sudden flow (of the fluid, which has penetrated into the pores of the core) offered by the pores of the core. It may be realized that when the pressure is suddenly released, this fluid must necessarily flow. The individual grains of the core are then forced from their adjoining grains, so that the core is disaggregated; in this way, the grains of the core are subjected to the least amount of stress possible.

When a liquid (such as the liquid carbon dioxide, previously mentioned) hasbeen pumped into the cell 1 to approximately 10,000 p.s.i. pressur and the rupture disc suddenly ruptures to release the pressure, causing disintegration of the core as described, there comes a pressure (during the pressure drop mo atmosphere) at which the liquid in the cell 1 will flash into .a gas. The resulting large volume of gas will tend to canry paint of the disintegrated core away, and it must be separated from the expanding carbon dioxide. For this purpose (to wit, getting rid of the gas without losing the solid particles of the sample or core), the cyclone separator 25 is used. As previously stated, the tangential input the separator 25 comes from the chamber 2, by way of pipe or tube 13. This cyclone separator spins the heavier particles to the outside of the separator (from whence they fall down into the separator section 28), while the lighter gases stay in the center of the cyclone and are exhausted, by way of exhaust pipe 26. Thus, the high pressure gas is released, while at the same time substantially all of the sample (disaggregated core) is saved for later study.

It will be appreciated that the disaggregated core (i.e., the core particles) is recovered by removing the closure 4- to gain access to chamber 2, and by removing the separator section 28. The core particles are thus collected from both the vessel 1 and the cyclone separator 25.

It is highly desirable to utilize, for the compressible fluid that is pumped by pump 23, a fluid that is more compressible than is the core. Such a fluid is liquid carbon dioxide. It is a preferred type of liquid, but is by no means the only one that will function effectively. The nitrogen and carbon dioxide referred to hereinabove will leave the disaggregated core clean, such that no further cleaning is required before study. On the other hand, there are presently available highly compressible silicone oils that can be used, and high pressure gases such as air can be used, but these cause (at least in the case of the silicone oils), a cleaning problem, before the core can be studied.

In the case of a compressed gas such as air, the gas is more fluid in flowing through the pores of the core (that is to say, a liquid is less fluid in flowing through the pores, so that a liquid is more resistive to flow when the pressure is released). Thus, a higher pressure of compressed gas would have to be used for complete disintegration than is the case with a liquid.

Another type of core disintegrator is one that can be described as having a sealing-type plunger (piston) held in position by a strong spring. If this cell were pressurized to say 10,000 p.s.i. and the spring were capable of holding the plunger in position, there would be no differential pressure in the cell to cause the core to disintegrate. If an arrangement were made whereby this spring-loaded piston could be rapidly vibrated in such a way as to suddenly increase the volume of the cell (say by the use of an air hammer, hammering on the piston to further compress the spring), there could be a shock Wave created from the inside of the core, developing a pressure differential which would tend to separate the core into particles. This type of device, and method, would be especially desirable for use on cores which have very little porosity.

The invention claimed is:

1. A core disintegrating device comprising a closed vessel adapted to contain therein a core, means for feeding a compressible fluid under high pressure to the interior of said vessel, a gas-solids separator, and a pressure-responsive frangible disc closure sealing off the interior of said vessel from said separator.

2. A device according to claim 1, wherein said separator is a cyclone-type separator.

3. In combination, a closed vessel containing a core to be disintegrated, means for feeding a compressible fluid under high pressure to the interior of said vessel, thereby to force such fluid into the pores of the core, a gas-solids separator, and a pressure-responsive frangible disc closure sealing off the interior of said vessel from said separator.

References Cited by the Examiner UNITED STATES PATENTS 2,139,080 12/1938 Dean et a1 2411 X 2,515,542 7/1950 Yellott 2411 2,656,308 11/1953 Pettyjohn 2411 X 2,711,369 6/1955 Birdseye 2411 X 3,165,266 1/1965 Blurn et al. 24l1 ROBERT C. RIOR'DON, Primary Examiner. H. F. PEPPER, Assistant Examiner. 

1. A CORE DISINTEGRATING DEVICE COMPRISING A CLOSED VESSEL ADAPTED TO CONTAIN THEREIN A CORE, MEANS FOR FEEDING A COMPRESSIBLE FLUID UNDER HIGH PRESSURE TO THE INTERIOR OF SAID VESSEL, A GAS-SOLIDS SEPARATOR, AND A PRESSURE-RESPONSIVE FRANGIBLE DISC CLOSURE SEALING OFF THE INTERIOR OF SAID VESSEL FROM SAID SEPARATOR. 